ENH: add type stubs from numpy-stubs

Add the type stubs and tests from numpy-stubs. Things this entails:

- Copy over the stubs (numpy/__init__.pyi and
  numpy/core/_internal.pyi)
  - The only modification made was removing `ndarray.tostring` since
    it is deprecated
- Update some setup.py files to include pyi files
- Move the tests from numpy-stubs/tests into numpy/tests
  - Skip them if mypy is not installed (planning on setting up CI in a
    future PR)
  - Add a mypy.ini; use it to configure mypy in the tests
    - It tells mypy where to find NumPy in the test env
    - It ignores internal NumPy type errors (since we only want to
      consider errors from the tests cases)
  - Some small edits were made to fix test cases that were emitting
    deprecation warnings
 - Add numpy/py.typed so that the types are picked up in an
   installed version of NumPy

8 files changed, 236 insertions, 0 deletions

diff --git a/numpy/tests/fail/array_like.py b/numpy/tests/fail/array_like.py
new file mode 100644
index 000000000..a5ef5795f
--- /dev/null
+++ b/numpy/tests/fail/array_like.py
@@ -0,0 +1,22 @@
+from typing import Any, TYPE_CHECKING
+
+import numpy as np
+
+if TYPE_CHECKING:
+    from numpy.typing import ArrayLike
+else:
+    ArrayLike = Any
+
+
+class A:
+    pass
+
+
+x1: ArrayLike = (i for i in range(10))  # E: Incompatible types in assignment
+x2: ArrayLike = A()  # E: Incompatible types in assignment
+x3: ArrayLike = {1: "foo", 2: "bar"}  # E: Incompatible types in assignment
+
+scalar = np.int64(1)
+scalar.__array__(dtype=np.float64)  # E: Unexpected keyword argument
+array = np.array([1])
+array.__array__(dtype=np.float64)  # E: Unexpected keyword argument
diff --git a/numpy/tests/fail/fromnumeric.py b/numpy/tests/fail/fromnumeric.py
new file mode 100644
index 000000000..f158a1071
--- /dev/null
+++ b/numpy/tests/fail/fromnumeric.py
@@ -0,0 +1,101 @@
+"""Tests for :mod:`numpy.core.fromnumeric`."""
+
+import numpy as np
+
+A = np.array(True, ndmin=2, dtype=bool)
+A.setflags(write=False)
+
+a = np.bool_(True)
+
+np.take(a, None)  # E: No overload variant of "take" matches argument type
+np.take(a, axis=1.0)  # E: No overload variant of "take" matches argument type
+np.take(A, out=1)  # E: No overload variant of "take" matches argument type
+np.take(A, mode="bob")  # E: No overload variant of "take" matches argument type
+
+np.reshape(a, None)  # E: Argument 2 to "reshape" has incompatible type
+np.reshape(A, 1, order="bob")  # E: Argument "order" to "reshape" has incompatible type
+
+np.choose(a, None)  # E: No overload variant of "choose" matches argument type
+np.choose(a, out=1.0)  # E: No overload variant of "choose" matches argument type
+np.choose(A, mode="bob")  # E: No overload variant of "choose" matches argument type
+
+np.repeat(a, None)  # E: Argument 2 to "repeat" has incompatible type
+np.repeat(A, 1, axis=1.0)  # E: Argument "axis" to "repeat" has incompatible type
+
+np.swapaxes(a, 0, 0)  # E: Argument 1 to "swapaxes" has incompatible type
+np.swapaxes(A, None, 1)  # E: Argument 2 to "swapaxes" has incompatible type
+np.swapaxes(A, 1, [0])  # E: Argument 3 to "swapaxes" has incompatible type
+
+np.transpose(a, axes=1)  # E: Argument "axes" to "transpose" has incompatible type
+np.transpose(A, axes=1.0)  # E: Argument "axes" to "transpose" has incompatible type
+
+np.partition(a, None)  # E: Argument 2 to "partition" has incompatible type
+np.partition(
+    a, 0, axis="bob"  # E: Argument "axis" to "partition" has incompatible type
+)
+np.partition(
+    A, 0, kind="bob"  # E: Argument "kind" to "partition" has incompatible type
+)
+np.partition(
+    A, 0, order=range(5)  # E: Argument "order" to "partition" has incompatible type
+)
+
+np.argpartition(  # E: No overload variant of "argpartition" matches argument type
+    a, None
+)
+np.argpartition(  # E: No overload variant of "argpartition" matches argument type
+    a, 0, axis="bob"
+)
+np.argpartition(  # E: No overload variant of "argpartition" matches argument type
+    A, 0, kind="bob"
+)
+np.argpartition(
+    A, 0, order=range(5)  # E: Argument "order" to "argpartition" has incompatible type
+)
+
+np.sort(a)  # E: Argument 1 to "sort" has incompatible type
+np.sort(A, axis="bob")  # E: Argument "axis" to "sort" has incompatible type
+np.sort(A, kind="bob")  # E: Argument "kind" to "sort" has incompatible type
+np.sort(A, order=range(5))  # E: Argument "order" to "sort" has incompatible type
+
+np.argsort(a)  # E: Argument 1 to "argsort" has incompatible type
+np.argsort(A, axis="bob")  # E: Argument "axis" to "argsort" has incompatible type
+np.argsort(A, kind="bob")  # E: Argument "kind" to "argsort" has incompatible type
+np.argsort(A, order=range(5))  # E: Argument "order" to "argsort" has incompatible type
+
+np.argmax(a)  # E: No overload variant of "argmax" matches argument type
+np.argmax(A, axis="bob")  # E: No overload variant of "argmax" matches argument type
+np.argmax(A, kind="bob")  # E: No overload variant of "argmax" matches argument type
+
+np.argmin(a)  # E: No overload variant of "argmin" matches argument type
+np.argmin(A, axis="bob")  # E: No overload variant of "argmin" matches argument type
+np.argmin(A, kind="bob")  # E: No overload variant of "argmin" matches argument type
+
+np.searchsorted(a, 0)  # E: No overload variant of "searchsorted" matches argument type
+np.searchsorted(  # E: No overload variant of "searchsorted" matches argument type
+    A[0], 0, side="bob"
+)
+np.searchsorted(  # E: No overload variant of "searchsorted" matches argument type
+    A[0], 0, sorter=1.0
+)
+
+np.resize(A, 1.0)  # E: Argument 2 to "resize" has incompatible type
+
+np.squeeze(A, 1.0)  # E: No overload variant of "squeeze" matches argument type
+
+np.diagonal(a)  # E: Argument 1 to "diagonal" has incompatible type
+np.diagonal(A, offset=None)  # E: Argument "offset" to "diagonal" has incompatible type
+np.diagonal(A, axis1="bob")  # E: Argument "axis1" to "diagonal" has incompatible type
+np.diagonal(A, axis2=[])  # E: Argument "axis2" to "diagonal" has incompatible type
+
+np.trace(a)  # E: Argument 1 to "trace" has incompatible type
+np.trace(A, offset=None)  # E: Argument "offset" to "trace" has incompatible type
+np.trace(A, axis1="bob")  # E: Argument "axis1" to "trace" has incompatible type
+np.trace(A, axis2=[])  # E: Argument "axis2" to "trace" has incompatible type
+
+np.ravel(a, order="bob")  # E: Argument "order" to "ravel" has incompatible type
+
+np.compress(True, A)  # E: Argument 1 to "compress" has incompatible type
+np.compress(
+    [True], A, axis=1.0  # E: Argument "axis" to "compress" has incompatible type
+)
diff --git a/numpy/tests/fail/ndarray.py b/numpy/tests/fail/ndarray.py
new file mode 100644
index 000000000..5a5130d40
--- /dev/null
+++ b/numpy/tests/fail/ndarray.py
@@ -0,0 +1,11 @@
+import numpy as np
+
+# Ban setting dtype since mutating the type of the array in place
+# makes having ndarray be generic over dtype impossible. Generally
+# users should use `ndarray.view` in this situation anyway. See
+#
+# https://github.com/numpy/numpy-stubs/issues/7
+#
+# for more context.
+float_array = np.array([1.0])
+float_array.dtype = np.bool_  # E: Property "dtype" defined in "ndarray" is read-only
diff --git a/numpy/tests/fail/numerictypes.py b/numpy/tests/fail/numerictypes.py
new file mode 100644
index 000000000..dd03eacc1
--- /dev/null
+++ b/numpy/tests/fail/numerictypes.py
@@ -0,0 +1,13 @@
+import numpy as np
+
+# Techincally this works, but probably shouldn't. See
+#
+# https://github.com/numpy/numpy/issues/16366
+#
+np.maximum_sctype(1)  # E: incompatible type "int"
+
+np.issubsctype(1, np.int64)  # E: incompatible type "int"
+
+np.issubdtype(1, np.int64)  # E: incompatible type "int"
+
+np.find_common_type(np.int64, np.int64)  # E: incompatible type "Type[int64]"
diff --git a/numpy/tests/fail/scalars.py b/numpy/tests/fail/scalars.py
new file mode 100644
index 000000000..0dfc55124
--- /dev/null
+++ b/numpy/tests/fail/scalars.py
@@ -0,0 +1,67 @@
+import numpy as np
+
+# Construction
+
+np.float32(3j)  # E: incompatible type
+
+# Technically the following examples are valid NumPy code. But they
+# are not considered a best practice, and people who wish to use the
+# stubs should instead do
+#
+# np.array([1.0, 0.0, 0.0], dtype=np.float32)
+# np.array([], dtype=np.complex64)
+#
+# See e.g. the discussion on the mailing list
+#
+# https://mail.python.org/pipermail/numpy-discussion/2020-April/080566.html
+#
+# and the issue
+#
+# https://github.com/numpy/numpy-stubs/issues/41
+#
+# for more context.
+np.float32([1.0, 0.0, 0.0])  # E: incompatible type
+np.complex64([])  # E: incompatible type
+
+np.complex64(1, 2)  # E: Too many arguments
+# TODO: protocols (can't check for non-existent protocols w/ __getattr__)
+
+np.datetime64(0)  # E: non-matching overload
+
+dt_64 = np.datetime64(0, "D")
+td_64 = np.timedelta64(1, "h")
+
+dt_64 + dt_64  # E: Unsupported operand types
+
+td_64 - dt_64  # E: Unsupported operand types
+td_64 / dt_64  # E: No overload
+td_64 % 1  # E: Unsupported operand types
+td_64 % dt_64  # E: Unsupported operand types
+
+
+class A:
+    def __float__(self):
+        return 1.0
+
+
+np.int8(A())  # E: incompatible type
+np.int16(A())  # E: incompatible type
+np.int32(A())  # E: incompatible type
+np.int64(A())  # E: incompatible type
+np.uint8(A())  # E: incompatible type
+np.uint16(A())  # E: incompatible type
+np.uint32(A())  # E: incompatible type
+np.uint64(A())  # E: incompatible type
+
+np.void("test")  # E: incompatible type
+
+np.generic(1)  # E: Cannot instantiate abstract class
+np.number(1)  # E: Cannot instantiate abstract class
+np.integer(1)  # E: Cannot instantiate abstract class
+np.signedinteger(1)  # E: Cannot instantiate abstract class
+np.unsignedinteger(1)  # E: Cannot instantiate abstract class
+np.inexact(1)  # E: Cannot instantiate abstract class
+np.floating(1)  # E: Cannot instantiate abstract class
+np.complexfloating(1)  # E: Cannot instantiate abstract class
+np.character("test")  # E: Cannot instantiate abstract class
+np.flexible(b"test")  # E: Cannot instantiate abstract class
diff --git a/numpy/tests/fail/simple.py b/numpy/tests/fail/simple.py
new file mode 100644
index 000000000..b5e9d1b13
--- /dev/null
+++ b/numpy/tests/fail/simple.py
@@ -0,0 +1,10 @@
+"""Simple expression that should fail with mypy."""
+
+import numpy as np
+
+# Array creation routines checks
+np.zeros("test")  # E: incompatible type
+np.zeros()  # E: Too few arguments
+
+np.ones("test")  # E: incompatible type
+np.ones()  # E: Too few arguments
diff --git a/numpy/tests/fail/ufuncs.py b/numpy/tests/fail/ufuncs.py
new file mode 100644
index 000000000..b178a4ea4
--- /dev/null
+++ b/numpy/tests/fail/ufuncs.py
@@ -0,0 +1,5 @@
+import numpy as np
+
+np.sin.nin + "foo"  # E: Unsupported operand types
+np.sin(1, foo="bar")  # E: Unexpected keyword argument
+np.sin(1, extobj=["foo", "foo", "foo"])  # E: incompatible type
diff --git a/numpy/tests/fail/warnings_and_errors.py b/numpy/tests/fail/warnings_and_errors.py
new file mode 100644
index 000000000..7390cc45f
--- /dev/null
+++ b/numpy/tests/fail/warnings_and_errors.py
@@ -0,0 +1,7 @@
+import numpy as np
+
+np.AxisError(1.0)  # E: Argument 1 to "AxisError" has incompatible type
+np.AxisError(1, ndim=2.0)  # E: Argument "ndim" to "AxisError" has incompatible type
+np.AxisError(
+    2, msg_prefix=404  # E: Argument "msg_prefix" to "AxisError" has incompatible type
+)